Anti-fracture, water-resistant, masonry-bondable membrane

ABSTRACT

An anti-fracture, water-resistant, masonry-bondable membrane comprises a lamina having a central layer generally containing at least one ply of a flexible material, e.g., an organic polymer such as polyvinyl chloride, generally in the form of a sheet, and a non-woven fiber layer physically bonded to each side thereof. The formation of the lamina is generally accomplished by laminating a single, nonwoven layer to a layer or sheet of a flexible material in the presence of heat and pressure to produce a construction wherein the nonwoven fibers are partially embedded in the flexible material. Subsequently, two such constructions are bonded together under heat and pressure to produce essentially a four-ply lamina wherein the layers of flexible material such as a polymer are fused to one another. The flexible membrane lamina, when utilized between and bonded to an exterior masonry article such as ceramic tile and to a substrate such as concrete, is very effective in preventing any cracks from propagating from the substrate to the article. The flexible membrane also has very good hydrostatic water resistance.

FIELD OF INVENTION

The present invention relates to an anti-fracture, water-resistant,masonry-bondable membrane having a flexible central layer and a layer ofnonwoven fibers physically bonded to each side thereof.

BACKGROUND

Heretofore, various membranes have been utilized between an exteriormasonry article such as ceramic tile or marble and a masonry substratesuch as concrete or stone to form a water-resistant barrier as well as aflexible layer which prevents cracks in the substrate from propagatinginto the article. Such a particular membrane contained an exterior,nonwoven, fiber material which was chemically bonded to a polyvinylchloride intermediate layer on each side thereof by an adhesive. Such alamina had poor hydrostatic water resistance and generally poorbondability to masonry bonding materials such as mortar or cement.Delamination would thus readily occur between the membrane and themasonry bonding material.

SUMMARY OF THE INVENTION

A flexible, anti-fracture, water-resistant membrane comprises a laminacontaining a central layer of a flexible material such as a polymerwhich is physically bonded on each side to a layer of nonwoven fibers.Although the lamina is relatively thin, it has good hydrostatic waterresistance and good bonding to masonry bonding materials. The lamina isreadily made by laminating a nonwoven fiber layer to a layer of aflexible material through the application of heat and pressure, andsubsequently laminating the aforesaid layers together by heat andpressure, with the resultant lamina containing the two flexible layersfused to one another. When utilized as an intermediate membrane in athin-set application, e.g., ceramic tile, bonded to a masonry substrate,the membrane is effective in forming a water or moisture barrier as wellas preventing the propagation of cracks from the substrate to the tile,and the nonwoven layers which have fibers protruding therefrom result inenhanced adhesion with the substrate and the tile.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross-sectional view of a lamina of the present inventionwherein a flexible polymer physically bonded to a layer of nonwovenfibers is fuse-bonded to a similar flexible polymer which is alsophysically bonded to a layer of nonwoven fibers.

FIG. 2 is a cross-sectional view showing a ceramic tile indirectlybonded by mortar through the flexible membrane lamina of the presentinvention to a concrete substrate.

DETAILED DESCRIPTION OF THE INVENTION

The membrane of the present invention is shown in FIG. 1 wherein likereference characters indicate like parts. The membrane, generallyindicated by the numeral 10, is a lamina generally containing a flexiblelayer 12 in the form of a sheet or film. Layer 12 can generally be anyflexible material such as an organic polymer, e.g., thermoplastic,amorphous, etc., which acts as a barrier to water and is capable ofundergoing heat fusion with a nonwoven fiber layer. Examples of specificflexible polymers include chlorinated polyethylene, polyacrylate,polypropylene, polyurethane, with plasticized polyvinyl chloride beingpreferred. Optionally, a preferred flexible polymer is a copolymer madefrom vinyl chloride monomers and small amounts of comonomers such asesters of acrylic acid wherein the ester portion has from 1 to 12 carbonatoms, for example, methyl acrylate, ethyl acrylate, butyl acrylate,octyl acrylate, cyanoethyl acrylate, and the like; vinyl acetate; estersof methacrylic acid wherein the ester portion has from 1 to 12 carbonatoms, such as methyl methacrylate, ethyl methacrylate, butylmethacrylate, and the like; styrene and styrene derivatives having atotal of from 8 to 15 carbon atoms such as alpha-methylstyrene, vinyltoluene, or chlorostyrene; vinyl naphthalene; diolefins having a totalof from 4 to 8 carbon atoms such as butadiene, isoprene, and includinghalogenated diolefins such as chloroprene or monoolefins having from 2to 10 carbon atoms and preferably 2 to 4 carbon atoms; and mixtures ofany of the above. The amount of the comonomer is generally up to about30 percent by weight and desirably up to 20 percent by weight.

Regardless of whether polyvinyl chloride homopolymer or copolymer isused, the inherent viscosity thereof according to ASTM-D-1240-60, MethodA, in cyclohexane at 20° C., is generally from about 0.85 to about 1.10,and preferably from about 0.90 to about 0.96.

When the flexible material layer is a polymer, it can containconventional additives in conventional amounts, such as processing aids,mildew-resistant compounds, light and heat processing stabilizers suchas epoxidized soybean oil, lubricants such as stearic acid, flameretardants, pigments, and the like.

When the flexible layer is the preferred homopolymer of vinyl chlorideor a copolymer thereof, it is an important aspect of the presentinvention that less than conventional amounts of plasticizer be utilizedin order to obtain desirable physical properties such as those set forthbelow. Examples of conventional plasticizers include various phthalates,e.g., dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, aswell as various terephthalates. The amount of plasticizer for thisinvention is generally 65 parts or less, desirably from about 35 toabout 55 parts, and preferably from about 40 to about 50 parts by weightper 100 parts by weight of the vinyl chloride homopolymer or copolymerresin.

Regardless of whether a vinyl chloride homopolymer or copolymer is used,the inherent viscosity thereof according to ASTM-D-1240-60, Method A, incyclohexane at 20° C., is generally from about 0.85 to about 1.10, andpreferably from about 0.90 to about 0.96.

The thickness of the flexible layer 12 is generally from about 12.5 milsto about 25 mils (from about 0.318 to about 0.635 millimeters),desirably from about 14 to about 22 mils (from about 0.356 to about0.559 millimeters), and preferably from about 15 to about 20 mils (fromabout 0.381 to about 0.508 millimeters).

Nonwoven fiber layer 14, desirable in the form of a mat, is attached toflexible polymer layer 12. More specifically, nonwoven layer 14 isphysically bonded to the flexible layer through the application ofpressure and heat. The process of physically laminating the two layerstogether involves pressing the two layers or sheets together as throughthe use of a calender roll or other appropriate laminating apparatus ata pressure of from about 125 to about 450 (from about 2,232 to about8,036) desirably from about 135 to about 350 (from about 2,411 to6,250), and preferably from about 150 to about 200 pounds per linearmeter) with the calender rolls being heated to a temperature of fromabout 280° F. to about 350° F. (from about 138° C. to about 177° C.),desirably from about 300° F. to about 335° F. (from about 149° C. toabout 186° C.), and preferably from about 300° F. to about 320° F. (fromabout 149° C. to about 160° C.). The flexible material such as a polymerand/or the nonwoven layer can optionally be preheated to approximatelythe same temperatures. Such temperatures are generally above thesoftening point of the flexible material, e.g., a polymer, but below themelting point thereof. An alternate laminating method is extruding theflexible material and subsequently running it through a nip roll withthe nonwoven layer to form the two-ply laminate. Generally, the flexiblematerial fed to the laminating apparatus exists at an elevatedtemperature as from about 270° F. to about 350° F. (from about 132° C.to about 77° C.) inasmuch as it is usually generally fed directly from aBanbury or an extruder, etc., to the laminating apparatus and is soft.Regardless of the particular type of laminating apparatus utilized, thenonwoven layer is partially pressed into the soft, flexible material andis physically bonded thereto; that is, no chemical bond, as generated bya chemical reaction, exists. Neither is a separate adhesive used. It isimportant that the nonwoven layer be only partially embedded in theflexible polymer layer so that the remaining portion thereof stillpossesses outward protruding fibers or a rough surface, and can form aneffective bond, i.e., be adhered, to a masonry bonding material. Theamount of fibers embedded is generally from about 20 percent to about 80percent, desirably from about 30 percent to about 70 percent, andpreferably from about 40 to about 60 percent by volume.

Nonwoven fiber layer 14 can be generally any type of synthetic nonwovenmaterial with specific examples including polypropylene, polyester, andnylon, and the like, with polyester such as polyethylene phthalate beingpreferred. The thickness of the nonwoven layer is generally from about 2to about 6 mils (from about 0.051 to about 0.152 millimeters), desirablyfrom about 3 to about 5 mils (from 0.076 to about 0.127 millimeters),with from about 4 to about 5 mils (from about 0.102 to about 0.127millimeters) being preferred.

Optionally, a second nonwoven fiber layer as described above can belaminated and physically bonded to the remaining side of the flexiblelayer, not shown, such that the resulting lamina contains only onecentral flexible layer. The process and apparatus for forming such alamina as well as the various layers thereof can be the same as setforth above, except that desirably the single-ply flexible layer isgenerally about twice as thick so that the formed membrane has suitablephysical properties such as hydrostatic or water burst resistance,modulus, and tensile strength, with regard to its intended end use.

A preferred lamina membrane of the present invention is shown in FIG. 1wherein another or second nonwoven fiber layer 24 is physically bondedto another or second flexible layer 22. Nonwoven fiber layer 24 can bethe same or different than nonwoven layer 14 and flexible polymer layer22 can be the same material or a different material than flexible layer12 and each layer can be made of any of the types of materials describedhereinabove. Once a second flexible layer 22 having a physically bondednonwoven layer 24 has been made under heat and pressure in a manner asset forth above, the two articles can be dual-laminated to form thepreferred four-ply, anti-fracture, water-resistant membrane of thepresent invention. The dual laminating process is conducted utilizingconventional laminating equipment such as a calender roll with theflexible materials of each article being heated and subsequently fusedtogether under pressure and heat. Suitable pre-heat temperatures of eachlayer 12 and 22, independently, are from about 250° F. to about 350° F.(from about 121° C. to about 177° C.) and desirably from about 280° F.to about 300° F. (from about 138° C. to about 149° C.). The temperatureof the laminating calender roll is generally from about 260° to about320° F. (from about 127° C. to about 160° C.), desirably from about 275°to about 310° F. (from about 135° C. to about 154° C.), and preferablyfrom about 290° F. to about 300° F. (from about 143° C. to about 149°C.), with the pressure exerted on each dual-ply component or articlebeing from about 180 to about 450 (from about 3,214 to about 8,036),desirably from about 200 to about 400 (from about 3,572 to about 7,143)and preferably from about 225 to about 350 pounds per linear inch (fromabout 4,018 to about 6,250 kilograms per linear meter).

An advantage of the dual lamination step is that when flexible layers 12and 22 are polyvinyl chloride, they often inherently contain pinholestherein and the heat-fusing of one layer to the other eliminates suchpinholes and thus significantly decreases, if not eliminates, thepenetration of water or vapor therethrough. The peel strength of the onepolymer layer to the second polymer layer is generally from about 2 toabout 6.5 pounds per linear inch (from about 35.7 to about 116.1) andpreferably from about 4 to about 6 pounds per linear inch (from about71.4 to about 107.1 kilograms per linear meter). The physical bondbetween the nonwoven fiber layer and its associated flexible polymerlayer is stronger than the fused polymer bond layers 12 and 22.

Due to its good physical properties, the four-ply lamina of the presentinvention containing two central layers of a flexible material issuitable for use as a flexible membrane located between an article whichis to be bonded to a masonry substrate. For example, the above-describedlamina of FIG. 1 desirably has a hydrostatic or water burst resistanceof at least 100 pounds per square inch (6.894×10⁵ newtons/square meter)a 150 percent modulus of from about 1,200 to about 1,800 or 2,000 poundsper square inch (from about 82.728×10⁵ to about 137.88×10⁵newtons/square meter) and desirably from about 1,400 to about 1,600 psi(from about 96.516×10⁵ to about 110.304×10⁵ newtons/square meter).

FIG. 2 shows lamina 10 of the present invention used as ananti-fracture, water-resistant membrane in a masonry environment orconstruction. Specifically, exterior article 30 is indirectly bonded viathe lamina 10 of the present invention to a masonry substrate 40. Theexterior article 30 is generally a thin-set article of masonryconstruction, that is, brick, ceramic tile, marble, stone, or the like.The exterior article 30 is typically bonded to the membrane laminathrough the use of a masonry bonding material 50 such as mortar, cement,or the like. Due to the fact that nonwoven fiber layer 24 is physicallybonded and thus partially embedded in flexible bonding layer 22, butstill has a substantial portion thereof residing upon the surface of thepolymer layer so as to present outwardly protruding fibers or a roughsurface, a strong bond is formed between the lamina and the masonrybonding material. Such a bond generally has the advantage of the absenceof (i.e., is free from) any delamination of the nonwoven layer 24.Similarly, the remaining nonwoven layer 14 is bonded through the use ofa masonry bonding material 50 to masonry substrate 40 which can beconcrete, stone, or the like. The net result is a flexible membraneinner liner which provides good water resistance or impermeability tothe exterior article of the masonry construction, as well as water burstresistance and, more importantly, effective crack propagationresistance. That is, should substrate 40 crack due to settling etc., theexistence of the flexible membrane inner liner 10 will absorb the stressand/or strain created by the height and/or width created by the crackand significantly retard, if not eliminate, the same from extending tothe exterior masonry article such as a ceramic tile.

While the above invention has been described with regard to a specificlamina and utilization thereof, it is to be understood that more than afour-ply lamina or a lamina containing a different arrangement of layersfrom that set forth in FIG. 1 can be utilized in a masonry construction,as shown in FIG. 2, or in a different construction.

The lamina of the present invention, whether containing a single or dualcenter layer, has been found to be very effective for the applicationsset forth immediately below, and generally has a break strength in themachine direction (i.e., calender) of at least 50 pounds and up to about75 pounds, preferably from about 55 to about 65 pounds (from 23 to 34kilograms and preferably from 25 to 29 kilograms), and in thecross-direction from at least about 40 to about 60 pounds and preferablyfrom about 45 to about 55 pounds (from about 18 to about 27 kilogramsand preferably from about 20 to about 25 kilograms). The tensilestrength in the machine direction is generally at least 1,100 psi toabout 1,800 psi (at least 76×10⁵ to about 124×10⁵ newtons per squaremeter), and preferably at least 1,400 to about 1,600 (at least about96×10⁵ to about 110×10⁵ newtons per square meter. The crack resistanceis generally 25° F. or lower (minus 4° C. or lower) and preferably 10°F. or lower (minus 12° C. or lower). The maximum shrinkage of the laminais desirably 5 percent with 3 percent or less being preferred.

The present invention is suitable for use in shopping centers and malls,patios, basement floors, cementitious backer boards, and the likewherever thin-set exterior masonry articles such as ceramic tiles,marble, and the like are to be applied via an anti-fracture,water-resistant membrane to a masonry substrate.

The invention can be more fully understood and appreciated by referenceto the following example which serves to illustrate, but is not intendedto limit, the invention.

EXAMPLE

A pair of identical two-ply lamina were formed by physically bonding anonwoven fiber layer to a plasticized polyvinyl chloride layer bycalendering the two layers at a temperature of about 300° F. (149° C.)and at a pressure of about 180 pounds per linear inch (3,214 kilogramsper linear meter). A four-ply membrane having a pair of polyvinylchloride layers which are fused together to form the inner layers and apair of nonwoven fiber outer layers physically bonded to each of thepolyvinyl chloride layers was formed by dual laminating the pair ofidentical two-ply lamina. The four-ply membrane was formed by placingthe pair of identical two-ply lamina in overlaying relationship with thepolyvinyl chloride layers of each two-ply lamina facing and abutting oneanother and passing the overlaying pair of two-ply lamina through a pairof calendering rollers at a temperature of about 300° F. (149° C.) andat a pressure of about 275 pounds per linear inch (4,911 kilograms perlinear meter). The polyvinyl chloride layers were The BFGoodrich CompanyGeon® vinyl homopolymer having an intrinsic viscosity of approximately0.93. Each of the two polyvinyl chloride layers had an average thicknessof about 17 mils (0.43 millimeters) so that the total thickness of thepolyvinyl chloride layers of the four-ply membrane was about 34 mils(0.86 millimeters). The nonwoven fiber layer was made of polyester(polyethylene terephthalate) fibers and had a thickness of about 4 mils(0.102 millimeters). The polyester was manufactured by Reemay Companywith 4-denier fibers and weighed 1.25 ounces per square yard.

Various properties of the resulting four-ply membrane of the inventionwere measured. The results and the methods used are listed in Table I.

The results show that a strong, relatively thin, lightweight,water-resistant membrane having good tear resistance, dimensionalstability, cold crack resistance, burst resistance and mildew resistanceproperties has been provided by the invention disclosed herein.

                  TABLE I                                                         ______________________________________                                        FINISHED PRODUCT TEST RESULTS                                                 TEST NAME TEST METHOD  RESULTS                                                ______________________________________                                        Total Weight                                                                            ASTM D-751   31.3 Oz. per Sq. Yd ± 3 oz.                         Thickness ASTM D-751   0.042 In. Avg. Std. Dev. =                                                    0.0009 in.                                             Peel Strength                                                                           ASTM D-751   5.0 lb./in. avg. 3.5-6.5 lb./in.                       (Adhesion)             range                                                  Vinyl (Layer                                                                  12) to Vinyl                                                                  (Layer 22)                                                                    Peel Strength                                                                           ASTM D-751   Internal bonding of vinyl                              (Adhesion)             layer 12 to vinyl layer 22                             Fabric (Layer          is less than the                                       14) to Vinyl           bonding strength between                               (Layer 12)             fabric 14 and vinyl 12 or                                                     fabric 24 and vinyl 22.                                Breaking  ASTM D-751   Machine Direction =                                    Strength =             62 avg. lb. force std. dev.                            (1" strip              3.1 lb.                                                tensile)               Cross machine = 50 avg.                                                       lb. force std. dev. = 3.76 lb.                         Tensile   ASTM D-882   Machine direction = 1502 avg.                          Strength               psi std. dev. = 81.1 lb.                                                      Cross Machine = 1135 Avg.                                                     psi std. dev. = 91 lb.                                 Trapezoid Tear                                                                          ASTM D-751   Machine direction = 63 lb.                             lb.                    avg. std. dev. = 5.0                                                          Cross machine = 62 lb. avg.                                                   std. dev. = 7.2 lb.                                    Dimensional                                                                             1 1/2 minutes in                                                                           Machine direction = 3%                                 Stability Boiling Water                                                                              shrinkage avg.                                                                Cross machine = 1.3%                                                          growth avg.                                            Cold Crack                                                                              ASTM D-1790  No cracks at +10° F.                            Resistance                                                                    Masland Impact                                                                Burst     FTMS-191 A   121 psi avg. std. dev. =                               Resistance                                                                              Method 5512  4.9 psi                                                          (Hydrostatic                                                                  Pressure)                                                           Mildew    Pink Stain Test                                                                            Clear zone of inhibition                               Resistance                                                                    ______________________________________                                    

While in accordance with the Patent Statutes, the best mode andpreferred embodiment has been set forth, the scope of the invention isnot limited thereto, but rather by the scope of the attached claims.

What is claimed is:
 1. An anti-fracture, water-resistant,masonry-bondable membrane comprising:a lamina having a central layercomprising at least one ply of a flexible material which is aplasticized vinyl chloride homopolymer or copolymer, and a nonwovenfiber layer directly physically bonded to each side of said centrallayer, said central layer having a thickness of from about 0.71 to about1.11 millimeters, the amount of said plasticizer being about 35 to about55 parts by weight for every 100 parts by weight of said vinyl chloridehomopolymer or copolymer, and said lamina having a hydrostatic pressureresistance of at least 6.89×10⁵ newtons/square meter.
 2. A membraneaccording to claim 1, wherein said central layer is two plies ofheat-fused polyvinyl chloride or a copolymer of vinyl chloride, andwherein said nonwoven fiber is polyester.
 3. A membrane according toclaim 2, wherein the vinyl to vinyl peel strength is at least 36kilograms/linear meter, and wherein said membrane is crack free whensaid membrane is subjected to a Masland impact test at -4° C.
 4. Amembrane according to claim 2, wherein the peel strength between the twoplies of the central layer is at least 36 kilograms/linear meter, andwherein said membrane is crack free when said membrane is subjected to aMasland impact test at -12° C.
 5. A membrane according to claim 1,having a breaking strength in the machine direction of a machine used tofabricate said membrane of at least 23 kilograms, and a tensile strengthof at least 76×10⁵ newtons/square meter.
 6. A membrane according toclaim 4, having a breaking strength in the machine direction of amachine used to fabricate said membrane of at least 25 kilograms, and atensile strength of at least 96×10⁵ newtons/square meter.